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3 years ago

A motorboat takes 5 hours to travel 100 kilometers going upstream. The return trip takes

Mathematics

1 answer:

tatuchka [14]3 years ago

8 0

Step-by-step explanation:

Let's say b is the rate of the boat in still water, and c is the rate of the current.

Distance = rate × time

Going upstream:

100 = (b − c) (5)

20 = b − c

Going downstream:

100 = (b + c) (2)

50 = b + c

Solve the system of equations using substitution or elimination. Using elimination, add the equations together:

70 = 2b

b = 35

c = 15

The boat's speed is 35 km/h, and the current's speed is 15 km/h.

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he number of surface flaws in plastic panels used in the interior of automobiles has a Poisson distribution with a mean of 0.02

Yakvenalex [24]

Answer:

a) 98.01%

b) 13.53\%

c) 27.06%

Step-by-step explanation:

Since a car has 10 square feet of plastic panel, the expected value (mean) for a car to have one flaw is 10*0.02 = 0.2

If we call P(k) the probability that a car has k flaws then, as P follows a Poisson distribution with mean 0.2,

$P(k)= \frac{0.2^ke^{-0.2}}{k!}$

In this case, we are looking for P(0)

$P(0)= \frac{0.2^0e^{-0.2}}{0!}=e^{-0.2}=0.9801=98.01\%$

So, the probability that a car has no flaws is 98.01%

Ten cars have 100 square feet of plastic panel, so now the mean is 100*0.02 = 2 flaws every ten cars.

Now P(k) is the probability that 10 cars have k flaws and

$P(k)= \frac{2^ke^{-2}}{k!}$

and

$P(0)= \frac{2^0e^{-2}}{0!}=0.1353=13.53\%$

And the probability that 10 cars have no flaws is 13.53%

Here, we are looking for P(1) with P defined as in b)

$P(1)= \frac{2^1e^{-2}}{1!}=2e^{-2}=0.2706=27.06\%$

Hence, the probability that at most one car has no flaws is 27.06%

6 0

3 years ago

Read 2 more answers

Given g(x) = x² - 6x - 16, which statement is true?

inn [45]

The correct choice of this question with the given polynomial is "The zeros are -2 and 8, because the factors of g are (x + 2) and (x - 8)". (Correct choice: H)

<h3>How to analyze a second orden polynomial with constant coefficients</h3>

In this case we have a second order polynomial of the form x² - (r₁ + r₂) · x + r₁ · r₂, whose solution is (x - r₁) · (x - r₂) and where r₁ and r₂ are the roots of the polynomial, which can be real or complex numbers but never both according the fundamental theorem of algebra.

If we know that g(x) = x² - 6 · x - 16, then the factored form of the expression is g(x) = (x - 8) · (x + 2). Hence, the correct choice of this question with the given polynomial is "The zeros are -2 and 8, because the factors of g are (x + 2) and (x - 8)". $\blacksquare$